Process for the carbonization of



May 28, 1940. 'r. RE-ICHERT 2,202,231

PROCESS FOR THE CARBONIZATION OF WOOD AND SIMILAR MATERIALS Filed March11, 1938 G175 OUTLET SQ g. OXYGEN-FREE G445 INLET G55 OUTLET I gwua/wtobTHEOPH/L 17E 619E6 7,-

Patented Me; 28, 1940 2,202,231

PROCESS FOR THE CARBONIZATION OF WOOD AND SIMILAR MATERIALS TheophilReichert, Brilon Wald, Germany, as-

signor, by mesne assignments, to Chemical Marketing Company Inc.,' NewYork, N. Y.

Application March 11, 1938, Serial No. 195,415 In Germany March 13, 19373 Claims. (01. 202-15) The invention relates to a process for thecarundesirable. This speed should not exceed about bonization of woodand similar materials. It 50 cm. per second, and advantageously shouldespecially relates to that type of carbonization not exceed 20 cm. persecond. in which all of the heat is supplied to the wood By maintainingthe speed thus within a range 5 by heating gases, and no other heatingof the of 1 to 50 cm. per second, it is possible to obtain 5 wood isprovided. high yields under conditions such that separation Suchprocedures have presented certain difilof the distillation products iseasily possible. culties since the large amounts of gas used make Evenpredried wood can be thus treated with it difflcult to condense or washout the distillaexcellent results. In carrying out the operation,

tion products. Where attempts have been made all that is necessary is toprovide a number oi 10 to reduce the amount of s, ver at andthermometers at diiferent heights in the retort, a e io in yield havegenerally resultedand to vary the speed of the circulating gases in TheP e invention Provides a manner of accordance with the indications ofthese theriz ns o S0 85 to Obtain high yields mometers so that thetemperatures in the upper while utilizing a relatively small amount ofcirlayers are not less t t t, i th carboniza- -15 culating gases so thatit is easy to recover the t zmm distillation products of the wood.Example 1 Suitable retorts for use in the process herein disclosed areshown in the drawing. Fig. 1 shows An up sht a ted carbonization retort-10 a retort with an inclination of 60 for the upper with a capaclty ofapproxlmately 100 cubic wall and 4 for the lower n. Fig 2 shows 55 terswas filled with about 40 cubic meters of wood for the upper wall and 45for the lower wa1l a moisture COntEnt Of 22%- Hot gases Were In order tocarry out t process, it has been introduced at the top of the retort andpassed found that the most important feature is the downwardlytherethrough. these a es when inlinear speed of movement of thecirculating gas having a temperature of 450 C. to 500 as it passesthrough the wood, and by suit 1 C. The gases were introduced at a rateof about 2 regulation of this linear speed improved results t0 3 p cond,and his rate was mainmaybe obtained regardless of the volume ofcartained in such a manner by the observation Of bonization gas per unitof wood passing through thermometers that no temperature diiferences theretort. By suitable adjustment of the linear occurred in the variouszones. Carbonization be- 30 speed we havefound it possible to carry outthe gan promptly and was completed without percarbonization under thebest conditions, regardmitting the operat to st p- Du th a n less of themoisture content of the wood. For period of the carbonizationdistillation products this purpose it is important that the linear speedescaped at the lower part of the retort at temshould lie within acertain range. peratures between 60 and 150 C. The yield per 35 In theordinary carbonization of wood by cubic meterof wood was as follows:heated circulating gases the temperature in the I Kilogram carbonizationzone, which gradually moves down- Acetic acid 43 to 44 wardly throughthe mass of wood during the car- Wood alcohol 145 bonization process, ishigher than the tempera- Wood t I 639 so ture of the previouslycarbonized layers above Charcoal 200 the carbonization zone. This istrue at very low u arspeeds of t circulating gases, If t The charcoalwas uniformly charred throughout. rate of circulation is increased, itwill be found Various gases may be used as heating ga 45 that at acertain point the temperature excess Such as t on gases from furnaces orthe 45 of the carbonization layer over the upper layers like exhaustEases te mbus on endisappears. When this point is reached, decreasesgines. Also gases produced by the burning of in yield are avoided, andan economical process liquid or dust-like fuels may be utilized asheating is thereby possible. In other words, according gases. Preferablythe combustible gases obtained 5 to the invention it is important thatthe linear from the carbonization are used, partly as cirspeed of thecirculating gases should be high culating gases, while another part ofthese disenough to prevent a greater temperature in the tillationproducts are burned for heating the circarbonization zone than in thezones thereabove. culating gases. Flushing gases may also be used 0n theother hand, the use of too high a speed as a heat carrier if thetemperatures of the carat the ordinary temperature and pressures isbonization material are maintained at least as 55 high as 500 C., andpreferably between 550 C. and 750 C.

The operation of the process was not obvious since it was to be expectedthat the exothermic reaction would occur to an increased degree undersuch conditions. It was furthermore feared that the surfaces of thepieces being carbonized would be so unfavorably influenced by the strongcarbonization reaction that proper carbonization would be impossible.Furthermore, a breaking up of the carbonization material was to beexpected which would produce a considerable decrease in the value of thecharcoal obtained. Also, and most important, such a process wouldapparently produce a decrease in the yield of the distillation productswhich are very sensitive to higher temperature, especially in thepresence of a catalytic material such as charcoal. However, according tothe invention, noneof these results arises, but on the contrary, a highyield is obtained.

Furthermore, since the carbonization can be carried out more quickly theapparatus in which it is carried out may be used oftener. The process isapplicable to wood, lignin, peat or other raw materials of vegetableorigin.

Example 2 A heat-insulated carbonization retort with a capacity of 100cm. was filled with wood having a moisture content of 20.5%.Carbonization gas from a preceding operation was heated in a superheaterand passed downwardly through the material so that it was heated to from550 C. to 600 C. The linear speed of the heating gases was kept at 1 to2 cm. per second. The distillation products were freed in condensersfrom tar, wood, vinegar and the like, and in washing towers from. woodalcohol. The combustible gases remaining were partly recirculated, andpartly burned for heating the recirculating gases. The

yields per cubic meter were as follows:

Kilograms Acetic acid "44 to 45 Wood alcohol- 15 Wood tar--- 63.5

Charcoal 200 these retorts cannot be completely fllled so that spacesoccur therein which trap the'gases and cause improper circulation. Thisprevents the constant movement of the gas at the desired velocity andthus makes it diillcult to maintain the temperature equal in thecarbonizing layer and the layers thereabove. According to the presentinvention such a disadvantage is avoided by making the upper part oftheretort in the form of a frustum, for example, a'conicalfrustum, theupwardly converging wall of which forms with the horizontal an angle ofat least and preferably and Such retorts can be filled uniformly andcompletely with wood or other carbonization material. As shown in Fig.1, the top part of theupper section may be in the shape of a frustum ofa cone. However, as shown in Fig. 2, this upper part may be also in theform of a curved surface, such as a spherical segment, a paraboloid andthe like. Various other shapes may be provided as long as the wallswhere they meet the vertical walls form the proper angle.

It has also been found that improved results can be obtained in myprocess if the lower downwardly converging walls of the retort are givena suitable angle, preferably an angle of 40 to 50 with the horizontal.Such a shape makes it possible for the material in the retort to slideout completely when the door in the bottom is opened to permit theremoval of the charcoal.

While I have described herein some embodiments of my invention, I wishit to be understood that I do not wish to limit myself thereby exceptwithin the scope of the appended claims.

I claim:

1. A process for carbonizing cellulosic material of vegetable origin toproduce high yields of acetic acid.and alcohol, which comprises fillinga retort the upper portion of the walls of which forms an upwardlyconverging angle of between 50 and 65 with the horizontal with suchmaterial, and passing hot oxygen-free gases downwardly through suchmaterial at a velocity of below 50 cm. per second, the velocity being soregulated that the temperature in the carbonization zone is not greaterthan that in the zones thereabove, and the temperature of the materialbeing carbonized being maintained between about 500 C. and 750 C.

2. In a process as claimed in claim 1, the lower walls of said retortforming a downwardly converging angle of from 40 to 50 with thehorizontal.

3. A process as claimed in claim 1, in which said velocity does notexceed 20 cm. per second.

THEOPHlL REICHERT.

